39 research outputs found
Hedge Fund Performance: The Canadian Market Case
With the growth of hedge fund industry, investors are interested in the possibility of replicating hedge funds returns by using market indexes. Most papers on the hedge fund performance are based on data prior the 2007-2008 financial crisis. This study uses monthly returns data for 59 Canadian hedge funds in Bloomberg database from January 2009 to September 2016 to investigate the hedge funds performance and possibility of replication in the post-crisis period. We follow Hzsanhodzicâs (2006) linear factor model to determine the significance of expected returns can be explained by six common risk exposures. We find that âcloneâ hedge funds returns would be hard to realize under Canadian market conditions by using current post-crisis data
Kinetic and thermodynamic investigations of CO2 gasification of coal chars prepared via conventional and microwave pyrolysis
This study examined an isothermal CO2 gasification of four chars prepared via two different methods, i.e., conventional and microwave-assisted pyrolysis, by the approach of thermogravimetric analysis. Physical, chemical, and structural behaviours of chars were examined using ultimate analysis, X-ray diffraction, and scanning electronic microscopy. Kinetic parameters were calculated by applying the shrinking unreacted core (SCM) and random pore (RPM) models. Moreover, char-CO2 gasification was further simulated by using Aspen Plus to investigate thermodynamic performances in terms of syngas composition and cold gas efficiency (CGE). The microwave-induced char has the largest C/H mass ratio and most ordered carbon structure, but the smallest gasification reactivity. Kinetic analysis indicates that the RPM is better for describing both gasification conversion and reaction rates of the studied chars, and the activation energies and pre-exponential factors varied in the range of 78.45â194.72 kJ/mol and 3.15â102,231.99 sâ1, respectively. In addition, a compensation effect was noted during gasification. Finally, the microwave-derived char exhibits better thermodynamic performances than the conventional chars, with the highest CGE and CO molar concentration of 1.30% and 86.18%, respectively. Increasing the pyrolysis temperature, gasification temperature, and CO2-to-carbon molar ratio improved the CGE
Allocation method of coupled PV-energy storage-charging station in hybrid AC/DC distribution networks balanced with economics and resilience
The hybrid AC/DC distribution network has become a research hotspot because of the wide access to multiple sources and loads. Meanwhile, extreme disasters in the planning period cause huge losses to the hybrid AC/DC distribution networks. A coupled PV-energy storage-charging station (PV-ES-CS) is an efficient use form of local DC energy sources that can provide significant power restoration during recovery periods. However, over investment will happen if too many PV-ES-CSs are installed. Therefore, it is important to determine the optimal numbers and locations of PV-ES-CS in hybrid AC/DC distribution networks balanced with economics and resilience. Firstly, the advantages of PV-ES-CS in normal operation and extreme disasters are analysed and the payment function is quantified accurately. Secondly, a bi-level optimal allocation model of PV-ES-CS in hybrid AC/DC distribution networks is established. In this model, the payment function using Nash equilibrium to balance economics and resilience is addressed at the upper-level, and the typical scenarios are simulated, and the optimal results are obtained using the genetic algorithm in lower level. Finally, a series of examples are analysed, which demonstrate the necessity of balancing economics and resilience, and advantages of DC lines in network restoration after disasters
Carbapenem-resistant Citrobacter freundii harboring blaKPCâ2 and blaNDMâ1: a study on their transferability and potential dissemination via generating a transferrable hybrid plasmid mediated by IS6100
IntroductionThe increase in clinical Enterobacteriaceae with dual carbapenemase has become a serious healthcare concern. It is essential to characterize the transferability and potential dissemination of blaKPCâ2- and blaNDMâ1-coharboring carbapenem-resistant Citrobacter freundii (CRCF).MethodsFour blaKPCâ2- and blaNDMâ1-coharboring CRCF strains were collected from our surveillance of the prevalence of carbapenem-resistant Enterobacteriaceae. The isolates were assessed using species identification, antimicrobial susceptibility testing, conjugation assays, whole-genome sequencing, plasmid stability, and fitness costs. Clonality, genome, plasmidome, and phylogeny were analyzed to reveal potential dissemination.ResultsThree ST523 blaKPCâ2- and blaNDMâ1-coharboring CRCF strains, collected from the same hospital within 1 month, exhibited high homology (both identity and coverage >99%), implying clonal dissemination and a small-scale outbreak. Moreover, the blaKPCâ2 and blaNDMâ1 genes were coharbored on an IncR plasmid, probably generated by a blaKPCâ2-harboring plasmid acquiring blaNDMâ1, in these three strains. Importantly, the IncR plasmid may form a transferable hybrid plasmid, mediated by IS6100 via transposition, with another IncFII plasmid included in the same C. freundii strain. Furthermore, the blaKPCâ2 and blaNDMâ1 of the fourth CRCF strain are located on two different non-transferable plasmids lacking complete transfer elements. Additionally, throughout the course of the 10-day continuous passage, the genetic surroundings of blaNDMâ1 in four CRCF strains were gradually excised from their plasmids after the 8th day, whereas they maintained 100% retention for blaKPCâ2. Genome and plasmidome analyses revealed that blaKPCâ2- or blaNDMâ1-harboring C. freundii were divergent, and these plasmids have high homology to plasmids of other Enterobacteriaceae.ConclusionClonal dissemination of ST523 blaKPCâ2- and blaNDMâ1-coharboring CRCF strains was detected, and we first reported blaKPCâ2 and blaNDMâ1 concomitantly located on one plasmid, which could be transferred with mediation by IS6100 via transposition. Continued surveillance should urgently be implemented